• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.799-808
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• 2021

This study was performed to investigate the extent of microbial contamination, the presence of enterotoxin genes, and the antibiotic susceptibility of Bacillus cereus in 58 red pepper plants and 43 environmental samples (soil, irrigation water, and gloves) associated with the plant cultivation. The detected counts of total aerobic bacteria, coliform bacteria, Escherichia coli, Bacillus cereus, and Staphylococcus aureus were lower in these samples, as compared to the regulations of standards for foods; moreover, pathogens, such as E. coli, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp., were not detected. Genes encoding hemolysin BL enterotoxins (hblA, hblC, and hblD) as well as non-hemolytic enterotoxins (nheA, nheB, and nheC) were detected in 23 B. cereus specimens that were isolated from the test samples and had β-hemolytic activity. Interestingly, B. cereus is resistant to β-lactam and susceptible to non-β-lactam antibiotics. However, in this case, the isolated B. cereus specimens exhibited a shift from resistant to intermediate in response to cefotaxime and from susceptible to intermediate in case of rifampin, trimethoprim-sulfamethoxazole, vancomycin, clindamycin, and erythromycin. Therefore, the levels of B. cereus should be monitored to detect changes in antibiotic susceptibility and guarantee their safety.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.322-340
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• 2021

Due to climate change and its consequential spring temperature rise, flowering time of Robinia pseudoacacia has advanced and a simultaneous blooming phenomenon occurred in different regions in South Korea. These changes in flowering time became a major crisis in the domestic beekeeping industry and the demand for accurate prediction of flowering time for R. pseudoacacia is increasing. In this study, we developed and compared performance of four different models predicting flowering time of R. pseudoacacia for the entire country: a Single Model for the country (SM), Modified Single Model (MSM) using correction factors derived from SM, Group Model (GM) estimating parameters for each region, and Local Model (LM) estimating parameters for each site. To achieve this goal, the bloom date data observed at 26 points across the country for the past 12 years (2006-2017) and daily temperature data were used. As a result, bloom dates for the north central region, where spring temperature increase was more than two-fold higher than southern regions, have advanced and the differences compared with the southwest region decreased by 0.7098 days per year (p-value=0.0417). Model comparisons showed MSM and LM performed better than the other models, as shown by 24% and 15% lower RMSE than SM, respectively. Furthermore, validation with 16 additional sites for 4 years revealed co-krigging of LM showed better performance than expansion of MSM for the entire nation (RMSE: p-value=0.0118, Bias: p-value=0.0471). This study improved predictions of bloom dates for R. pseudoacacia and proposed methods for reliable expansion to the entire nation.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.374-382
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• 2021

In the present study, we analyzed the decay rate and nutrient dynamics during leaf litter decomposition of Pinus densiflora and Pinus thunbergii in Gongju for 60 months, from 2014 to 2019. P. thunbergii leaf litter decomposed faster than that of P. densiflora. The decay constant of P. densiflora and P. thunbergii leaf litter after 60 months was 3.02 and 3.59, respectively. The initial C/N ratio of P. densiflora and P. thunbergii leaf litter were 14.4 and 14.5, respectively. After 60 months, C/N ratio of decomposing P. densiflora and P. thunbergii leaf litter decreased to 2.26 and 3.0, respectively. The initial C/P ratio of P. densiflora and P. thunbergii leaf litter were 144.1 and 111.3. After 60 months elapsed, the C/P ratio of decomposing P. densiflora and P. thunbergii leaf litter decreased to 40.1 and 45.8, respectively. After 60 months, the percentage of the remaining N, P, K, Ca, and Mg in decomposing P. densiflora leaf litter was 231.08, 130.13, 35.68, 48.58, and 36.03%, respectively. After 60 months, the percentage of the remaining N, P, K, Ca, and Mg in decomposing P. thunbergii leaf litter was 143.91, 74.02, 28.59, 45.08, and 44.99%, respectively. The findings of the present study provide an insight into the forest ecosystem function of coniferous forests through the analysis of the amount of nutrient transfer into the soil through a long-term decomposition process; this information is intended to be used as basic data for preparing counter measures for future climate and ecosystem changes.

• Korean Journal of Organic Agriculture
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• v.29 no.2
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• pp.223-240
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• 2021

This study was carried out to investigate the economic value of organic wheat production using gelatin·chitin microorganisms in Gwangsan-gu, Gwangju city. The soil condition of experiment field was clay loam Jisan series. The organically cultivated fields were sprayed gelatin and chitin degrading bacteria. The test was performed at conventionally cultivated field and organically cultivated field. Emergence of weed on organically cultivated field was significantly higher than conventionally cultivated field which sprayed herbicide before seeding. Weed emergence have a critical impact on grain yield. Occurrence of diseases and insect pests were higher than conventionally cultivated fields. In 2019, the amount of lodging in conventionally cultivated field were higher than conventionally cultivated field. In 2020, lodging and wet injury were occur in both field. Comparing yield element between organically and conventionally cultivated experimental area, grain yield in organically cultivated field was shown slightly higher amount than conventionally cultivated field. However in the actual yield of 2019, organically cultivated field shows 20% deceased yield because of overgrown weed. In 2020, weed emergence and yellow mosaic virus by wet injury cause 30% decease in the grain yield in organically cultivated field. Content of protein, carbohydrates, ash, water and fat in the grain were not different significance. In 2019, net incomes of conventionally cultivated wheat was 461,031 won/0.1 ha while organically cultivated wheat was 443,437 won/0.1 ha. In the rate of income, conventionally cultivated field was 83.0% as against organically cultivated field (73.3%). In 2020, net incomes of organically cultivated wheat was 437,812 won/0.1 ha while conventionally cultivated wheat was 418,281 won/0.1 ha. In the rate of income, conventionally cultivated field was 81.6% as against organically cultivated field (73.0%).

• Journal of Wetlands Research
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• v.20 no.4
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• pp.398-409
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• 2018

Organic farming practices including loach based ecosystem-farming have been demonstrated to be effective in conjunction with rice farming to increase yield and quality. This new form of farming combines agriculture and fishery and is quickly developing into a new industry. The current study investigated the effect of rice-fish mixed farming system on the vegetation-diversity function. Vegetation within the four study sites was surveyed and analyzed based on plant taxonomy. The vegetation survey demonstrated that 127 taxa of 38 families, 100 genera, 107 species, and 20 varieties occurred within the study sites. A total of 15 plant species taxa occurred in the rice-fish mixed paddy fields with a fish habitat and did not occur in the conventional paddy field lacking fish habitat. This difference is thought to arise from differences in moisture requirements for vegetation. Life form analysis demonstrated differences in hemicryptophytes, therophytes, and hydrophytes according to fish habitat. The naturalized plants identified were also determined to be species widely distributed throughout Korea. Frequency analysis demonstrated that the rice-fish mixed paddy fields with a fish habitat had a high ratio of both obligate and facultative wetland plants relative to the conventional paddy field. Based on the study results, it is likely that vegetation-diversity will increase with environment diversity. However, no statistical significance was observed according to paddy types. Future research should aim to identify additional environmental factors, including the existence of fish habitat, habitat area, depth of fish habitat, hydrological parameters, water quality, and paddy soil environment, to enhance vegetation-diversity and biocultural diversity.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.337-349
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• 2021

This study aimed to isolate wild yeasts from water and soil sample of the Nonsan stream and Sapgyoho (lake) in Chungcheonnam-do, Korea, and to further characterize previously unrecorded wild yeast strains. In total, 102 strains, representing 55 different species of wild yeast were isolated from 95 samples collected from the Jangseoncheon and Ipchoncheon of Nonsan stream in Jellabuk-do and Chungcheonnam-do. Among these, 33 strains were isolated from alkalophilic yeast extract-peptone-dextrose (YPD) medium (pH 9.0), and 9 strains were isolated concurrently on general YPD medium (pH 6.5) and alkalophilic medium. Seventeen strains of Cryptococcus laurentii were predominantly isolated. Additionally, 65 strains, representing 27 different species of wild yeast were isolated from 58 samples obtained from Sapgyoho (lake). Among the 82 isolated wild yeast strains, 8 strains, including Candida fructus JSC 72-1(JSL-GGU 015), had not previously been recorded. All 8 previously unrecorded yeasts were oval in shape except C. fructus JSC72-1(JSL-GGU-015), and only the Filobasidium chernovii JSC39-1(JSL-GGU-013) strain formed spores. All strains except Pseudosydowia eucalypti JSC23-6(JSL-GGU-012) grew well in yeast extract-peptone-dextrose (YPD) and yeast extract-malt extract media and grew in vitamin-free medium. Four strains, including P.eucalypti JSC23-6(JSL-GGU-012) grew well in 15% NaCl-containing YPD medium. F.chernovii JSC39-1(JSL-GGU-013) and Sirobasidium intermedium JSC7-3(JSL-GGU-014) assimilated lactose, and five strains, including F. chernovii JSC39-1(JSL-GGU-013) also assimilated starch. All strains were resistant to 800 ppm of Ca, Cu, Li, and Mg ions.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.5
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• pp.1-13
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• 2019

This study is to derive a design alternative to the FECC (Forest Experience Center for Children) that meets the preschooler's preferences. For this purpose, preschooler participation is included in each phase of the FECC, the site perception phase, the deriving design elements phase, and the deriving design alternative phase. In this study, the process of the deriving design alternative phase was carried out with kindergarteners and preschoolers (6, 7 years olds; all 41 students) at Songsan-mulbit FECC in Gwangsan-gu, Gwangju. In order to derive the design alternatives, three detailed design processes (preschooler participation 2 times, researcher analysis 1 time), tool construction, and a preschooler participation workshop were conducted. The results of this study are as follows. First, as a result of the preschooler's design process, 41 designs were drawn, and an average of 7.66 spaces were drawn by each preschooler. The 6-year-old males designed the least (average 6.80 spaces) and the 7-year-old females designed the most (9.0 spaces). The physical and adventure play spaces were most common (38.9% to 48.7%) regardless of gender or age. To analyze the feasibility of the preschooler's design using a base map, the appearance of the physical environmental characteristics (7 items) in the site were analyzed in each of the 41 designs. As a result, the environmental characteristics were apparent a total 72 times overall. Similar environmental characteristics appearing more than once were apparent in 87.8% (26 designs) of designs. Second, three design alternatives were derived: APS- types (intensive planning of active play facility spaces) was presented in 15 designs, NS-types (planning focused on nature spaces) was presented in 14 designs, and SPS-types (planning focused on static play facility spaces) were presented 12 designs. Third, NS-type, which were finally selected through a preference assessment (5-point scale) and a comparative assessment of the three alternatives, has mainly natural spaces (forest space, forest path, shelter, natural exploration space, and ecological pond) and active play facility spaces, water play space and soil (sand) play spaces was appropriately designed. Therefore, the NS-type was analyzed as the design alternative that can fully accomplish all types of cognitive development through developed through play (functional play, constructive play, dramatic(symbolic) play).

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.483-493
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• 2011

Erosion control dams play a primary role in preventing or controlling natural disasters (landslide and debris flow etc.) and also conserve ecosystem in forested watersheds. This study examines structural characteristics of the dams such as the height of ecosystem control and the ecosystem permeability of the erosion control dams under standard drawings and the existing construction works. The objective of this study was to characterize the type classification of erosion control dams as ecosystem. Average permeability was highest on eco-piller dam (63.0%), followed in increasing order by wire rope (13.9%), silt dam (10.9%), multifunctional dam (7.2%), and gravity dam (0.4%). The height of ecosystem control was highest on gravity dam (3.2 m), followed in increasing order by multifunctional dam (1.7 m), wire rope dam (1.2 m), silt dam (0.6 m), and eco-piller dam (0.0 m). Criteria for defining the height of ecosystem control was indefinite. We grouped erosion control dams into three functional types (eco-connection, eco-semi connection, and eco-disconnection) by considering physical and structural characteristics such as the ecosystem permeability and the height of ecosystem control. The type of eco-connection (permeability > 20%) had connection areas from streambed to adjacent riparian areas, and these connection areas serve as ecosystem corridors for fauna and flora. Typical wildlife species includes mammals, reptiles, amphibians, and fishes. The type of eco-semi connection (5% < permeability < 20%) had < 2 m in the eco-barrier height from streambed, however, this type of dams partially serve as wildlife corridors and often provide fish ways. The type of eco-disconnection (permeability < 5%) had > 2 m in the eco-barrier height from streambed, thereby preventing wildlife movement.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.49-60
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• 2021

We examined the flow characteristics by direct runoff and base flow in a headwater stream during observed 59 rainfall events of flood season (June~September) from 2017 to 2020 yrs. Total precipitation ranged from 5.0 to 400.8 mm, total runoff ranged from 0.1 to 176.5 mm, and runoff ratio ranged from 0.1 to 242.9% during the rainfall events. From hydrograph separation, flow duration in base flow (139.3 days) was tended to be longer than direct runoff (78.3 days), while the contribution of direct runoff in total runoff (54.2%) was greater than base flow (45.8%). The total amount and peak flow of direct runoff and base flow had the highest correlation (p<0.05) with total precipitation and duration of rain among rainfall and soil moisture conditions. Dominant rainfall events for the total amount and peak flow of base flow were generated under 5.0~200.4 and 10.5~110.5 mm in total precipitation. However, when direct runoff occurred as dominant rainfall events, total amount and peak flow were increased by 267.4~400.8 and 169.0~400.8 mm in total precipitation. Therefore, the unique aspects of our study design permitted us to draw inferences about flow characteristic analysis with the contribution of base flow and/or direct runoff in the total runoff in a headwater stream. Furthermore, it will be useful for the long-term strategy of effective water management for integrated surface-groundwater in the forested headwater stream.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.385-393
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• 2022

The contamination level of inorganic arsenic, a human carcinogen, was investigated in 87 grains and 66 processed grain foods. Two inorganic arsenic species arsenite (As(III)) and arsenate (As(V)) and four organic arsenic monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine were analyzed using HPLC-ICP/MS with high separation and sensitivity and ICP/MS was used to quantify total arsenic. Inorganic arsenic was detected in all grains. And the total arsenic in grains consists of about 70-85% inorganic arsenic and about 10-20% DMA. The concentration of inorganic arsenic was high in rice and black rice cultivated in paddy soil with irrigated water, while the miscellaneous grain in field was low. Mean concentration of inorganic arsenic in rice germ, brown rice and polished rice was 0.160 mg/kg, 0.135 mg/kg, 0.083 mg/kg, respectively, indicating that rice bran contains more arsenic. In processed grain foods, inorganic arsenic concentration varied according to the kind of ingredients and content, and the detection amount was high in processed food with brown rice and germ. The arsenic content of all samples did not exceed each standard, but the intake frequency is high and it is considered that continuous monitoring is necessary for food safety.